131220705 has 128 divisors (see below), whose sum is σ = 285659136. Its totient is φ = 49766400.

The previous prime is 131220701. The next prime is 131220721. The reversal of 131220705 is 507022131.

It is not a de Polignac number, because 131220705 - 2² = 131220701 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (131220701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 804954 + ... + 805116.

It is an arithmetic number, because the mean of its divisors is an integer number (2231712).

Almost surely, 2^131220705 is an apocalyptic number.

131220705 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

131220705 is an abundant number, since it is smaller than the sum of its proper divisors (154438431).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

131220705 is a wasteful number, since it uses less digits than its factorization.

131220705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 131220705 is about 11455.1606274203. The cubic root of 131220705 is about 508.1603656495.

Adding to 131220705 its reverse (507022131), we get a palindrome (638242836).

The spelling of 131220705 in words is "one hundred thirty-one million, two hundred twenty thousand, seven hundred five".